Chain grate stoker



Sept. 27, 1932. v R CHADwlCK l ,879,732

CHAIN GRATE STOKER wf/MM SePt- 27, 1932- v. R. cHADwlcK CHAIN GHATE STOKER 4 sheets-sheet 2 Filed April 3. 1929 @www Sept. 27, 1932. v R, CHADwlCK 1,879,732

CHAIN 4GRATE STOKER Filed April 3. 1929 4 Sheets-Sheet Sept. 27, 1932. v R CHADW|CK ,879,732

CHAIN l@RATE STOKER Filed April .'5. 1929 4 Sheets-Sheet 4 Patented Sept. 27, 1932 wam y UNITED STATES PATENT OFFICE vnRNnn RUssnLLfeHAnwrex, or LONDON, ENGLAND eHAfrN GRATE s'roxnn Application filed April 3, 1929,V Serial No. 352,597, andin Great Britain May 3,'7-1928. v

This invention is for improvements in or relating to chain grate Astokers. for steamboilers or other furnaces of the type' wherein the air for combustion is supplied under g pressure, being Qfor example induced'iby steam-jets or by blowers, in the usual man.

ner. v l

One object Vof the invention-is to improve generally the construction of stokers of thev aforesaid type, whereby more perfect combustion of the fuel can be obtained with a view to ensuringsmokeless operation of the` furnaces.

According to one feature ofthe present invention an air-duct is provided at each side of the chain grate and each of these airducts extends longitudinally of the grate approximately from end to end thereof. Moreover, each duct has a wall arranged in close proximity to the grate's'o as to form a side wall -for the latter, each -of vthese side walls extending from the upper run ofthe grate to about the level of the lower Vrun thereof. i Y A In a convenient construction, the air-passage aforesaid extends substantially throughout the length of the grate in proximity thereto and is divided into twoseparate ducts arranged horizontally one above the other and in communication with one another at the rear end of the furnace, and means are provided at the front end of the furnace for admitting air to one duct, which air flows along said duct to the rear end of the furnace and returns along the other duct to the front end of the furnace where it enters said transl verse chamber. Preferably, air is admitted to the lower duct and returns along the up- Y per duet so that the air is graduallylheated during its passage to the grate. 1 According to another feature of the invention, a chain grate Stoker constructed as described in eitherof the two preceding paragraphs, comprising a plurality of airtroughs, and wherein theggrate is composed of a plurality of links which are interconi nected by means kof' pins passing throughv holes in lugs on said links may be provided with rollers which are mounted on said pins 5o between adjacent links at intervalstransverselyof the grate and are adapted to run on the upper edges of the sides of .the air# troughs aforesaid. Y. v Y

Other features of the invention will be'apparentv from the following description of one specific embodiment thereof, which will now be described by way of example, withfreference to the accompanying drawings, in Which p Y, w -v v Figure lis a longitudinal'section of a fur-V nace on the line l--l of Figure 2 with a chain grate Stoker. according to lthe inventionapplied thereto; c i

Figure ,2 is an end elevation, partly in section, on the line 2-2 of Figure 1,v and in.I 65 part diagrammatic;

Figure 3 is an enlarged sideelevation vof the rear end of the chain grate;

Figure v4 is an elevation, partly insection, onthe line 4 4 of Figure 3,. drawn to a still larger scale; i Y

Figure v5 is a section on the line 5 5 of Figure 4, drawn to the same scale as Figs;V ure3;` Y L y f Figure 6 is a perspective view of one o the links of the chain grate, and* a l Figure 7 is a similar view of a link constructed to accommodate the. roller-s aforesaid. y. Y

`Like reference numerals indicatelike parts in the various figures ofthe drawings.

The chain grate ismoun-ted on a unitary frame-structure which .comprises at each: side of the grate two air-ducts 10,11, whichA extend substantially throughout thelength of the grate in proximity thereto and are'y arranged horizontally oneabove the other. The partition` l2, separating theducts of eachv pair, terminates a'short distance from the rear-'end ,18 of the frame-structure to provide an opening 14 through which air can flow from the duct 10 into'the duct 11. Each of vthe ductsll 'communicates at the front end of the grate with a transverse air- Y t chamber 15. The rear wall of this air-cham- 9J ber is provided with apertures 16 that com-V municate f with six longitudinally arranged air-troughs 17, 'which are disposed beneath the upper run ofthe grate., andare integralV with, or. secured to, theair-ehamber afore- 3.2.-.

said. Each of the air-troughs diminishes in cross-sectional' area towards its rear end, thus assuring an even flow of the air for co-mbustion. rlhe air-troughs 17 are supported on transverse bars 18'carried by brackets 19 secured to the inner walls of the air-ducts 10. Air is admitted to the front ends of the ducts through injectors 2O provided with draught-inducing steam-jets 21. It will be appreciated that the air induced into the ducts 10 flows therealong to the rear end o-f the furnace whence it enters the ducts 11, along which it flows, into the transverse airchamber l and thence into the troughs 17 .n

In ord-er to ensure a satisfactory flow of the air, auxiliary steam-jets 22 are provided in the chamber 15 adjacent the ends ofthe troughs 17.

V'The'chain grate is composed of a pluralityv of links which are interconnected by means of-pins 23=passing through holesin lugs 24 on. said links.1' Rollers 25 Lare mounted oni kthe pins 23 between adjacent links at inter-V vals transversely of the grate, which rollers run on the upper edges" of thesides of the troughs 17. Onreference to Figure 2, it will be seen that in the construction illustrated, three sets of rollers 25 areprovided. The chain grate passes around polygonal y, drums 26, 27 at the frontand rear ends respectively of the grate, which drums are carried by shafts mounted in suitable bearings in the walls` of the air-ducts 10 and 11. Rollers 25 are sog arranged longitudinally of the grate that each in .turn will engage be'- tween adjacent teeth of appropriately dis-` posed sprocket-wheels 28, 29 on the drums 26, 27 respectively.

The chain grate is slowly moved through the furnace by rotating the shaft 30 on which the drum 26 is mounted. This rota,

tion may be effected by means of a wormwheel 31 on the shaft 30, which worm-wheel meshes with a worm 32 on a shaft 33 that can be rotated by any convenient mechanism in the usual manner.

The links-of the chain grate may be of Vany convenient construction which will permit air to pass-between them from the troughs 17 to th'efuel above. In the construction il.

lustrated in the drawings, each link is lprovided on each side with inclined ribs 34 which are spaced apartso as to provide airpassages 35 between them. These ribs 34 are so arranged that in the upper run o-f the grate the said air-passages slope upwardlyv towards the rear end of the furnace. It will be appreciated that owing totheinclination of said ribs they intercept the air leaving the -trough 17 with a minimum of resist-` ance. Moreover, the ribs 34 on one` setof linksiny the upper run of the grateare disl posed adjacent the air-spaces onthe next transverse set of links so'that a large number of narrow air-spaces are provided through which the air is distributed' in the` form of fine sprays, and consequently it is? thoroughly diused throughout the lire. The construction of the links is clearly shown in Figures 3 to 7, inclusive, of the drawings. All the links are similar, with the exception that those between which the rollers 25 are mounted have the lugs 24 and portions of the ribs 34`V out away, as shown at 36A (see Figures 5 and *7),to accommodate ythe said rollers.

The air-troughs 17 are provided at their i upper ends with inclined baiiies 37 which connect the sides of said troughs and between which air-spaces are formed whichslope upwardly towards the., rear end of the furnace. Thesebafflesare so arrangedV that the cross-sectional area of saidv air-spaces diminishesgradually towards the rear end of-the furnaceso as to regulate better the .1

admissioniof air through the chain grate, less air being required at the rear end thereof.

owing to the fuel lresting on that part of they grate being'partially consumed and of less depth.V

At the rea-r end `of the grate a dumpingplate 38 is provided, which dumping-plate is pivotally mounted at 39 in brackets 40 on the air-ductslO and 11. The forward end of saidpl'ato ,rests on the upper'walls 41 of l' theA-air-ducts 11 (see especially Figure2) at a sufficient distance from the rear end ofthe troughs 17.to permit air therefrom to circulate on the under-side of said plate. It

will be appreciatedthat fine ash" can pass underneath the plate 38 vinto the ashfpit 42 below, and that clinker will pass over the plate into said ash-pit. A door 43 hinged to supports 44 in the furnace shell normally prevents the admissionof airpto the ash-pit I 42 and Vis adapted to be opened by any convenient means, not shown, to permit clinker and ash to be removed periodically from vsaid pit. Y ,y L j Rollers 454mounted on spindlescarried in suitable bearings in thelower ends of the inner walls of the air-ducts 10 are. adapted to runen tracks 46 fixed to the shell 47 of the furnace, and from the'foregoing description it will be apparent that the unitary frame4` structureaforesaid comprising the air-ducts 10, 11, thertransverse air chamber 15 and the air-troughs 17, together with the chain grate` ico 53 which slopes upwardly from said partition. The fuel is fed into saidy hopper so that it falls on to said riddle which permits the fine fuel to pass therethrough into the compartment 52, while the coarse material falls into the compartment 5l. Thus, it will be seen that the coarse material falls first on to the chain grate and subsequently the fine fuel falls on to the layer of coarse niaterial, so that the possibility of `line material choking the air-passages between the links of the grate is minimized, if not entirely prevented. Y

At the rear of the compartment 5l of the hopper, an adjustable door 54, adapted to be actuated by any suitable mechanism in the usual manner is provided for regulating the depth of the fuel on the grate.

It is to be understood that the invention not restricted to the precise constructiorel details described, as, obviously, various modifications can be made without departing therefrom.

I claim l. A chain grate stoker of the type where-- in the air for combustion is supplied under pressure, comprising in combination a framestructure, an endless chain grate mounted thereon, an air-conduit extending subst-antially throughout the length of the grate in proximity thereto, which air-conduit is divided into two separate ducts arranged horizontallly one above the other and in com? munication with one another at the rear end of the grate, a transverse air-chamber at the front end of the grate in open communication with one of said ducts, means for ad-Y mitting air into the other duct at the front end of the grate, and a longitudinally arranged air-trough in communication with said transverse chamber and disposed beneath the upper run of the grate.

2. In a chain grate stoker having an endless chain grate, the combination of a number of air-troughs arranged side-by-side beneath and in close proximity to the upper run of said grate, a plurality of inclined bullies connecting the upper ends of the sides of said air-troughs and spaced apart to provide air-spaces between them, which baflies slope upwardly towards the rear end of the troughs and are so arranged that the cross sectional area of said air-spaces diminishes gradually towards the rear end of the grate, and means for admitting air for combustion into said troughs.

3. A chain grate stoker of the type wherein the air for combustion is supplied under pressure, comprising in combination an end` less chain grate, an air-conduit having a flow, and return chiots, extending longitudinally along each side of the grate, a transverse airchamber connecting said airconduits, a number of longitudinally arranged air-troughs leading from said air-chamber and disposed beneaththe upper run of the grate',an injector foradmitting air to at least one of said air-conduits,andf a number of steam-jets for inducing' a liow of air through the said conduits and chamber into the air-troughs'afore- 4. In a'chain gratestoker for a furnace,a chain grate mounted on a removable unitary framestructure which comprises at each side ofthegrate flow and return air-ducts extending longitudinally ofthe grate and arranged horizontally one abovethe other, a transverse air-chamber at the front end of the furnace communicating with each of said return ducts, a number kof air-troughs disposed longitudinally of and beneath the' upper run of the grate in close proximity thereto, which troughs diminish in cross-sectional area towards their rear ends and atV their front ends so arranged that the cross-sectional areaof said air-spaces diminishes towards the rear end of the furnace, a steam injector for 1nducing air into each of the flow ducts aforesaid, auxiliary steam jets arranged in the` transverse air chamber adjacent the inlet openings to the said air-troughs, and a dumping-plate which rests at its forward end on the rear end of the framestructure aforesaid and so as to permit air from said troughs to circulate on the underside ofsaid plate.V

5. The combination with a movable carriage, of a chain grate stoker mounted on said carriage, two longitudinal air-ducts one at each side of the chain grate and each having a wall forming a side wall for the latter, a transverse air-chamber communicating with said longitudinal air-ducts, at, least one longitudinally arranged air-trough inv communication'with said transverse chamber and situated beneath the upper run of the grate, and means for producing a How of air through Vsaid air-ducts and thence to the grate, all constructed and arranged to form t Vchain grate, of two longitudinal air-ducts `one extending'along each side of the chain grate and in close proximity thereto, atransverse air-chamber at one end of said grate com# municating with said longitudinal air-ducts, a number yof substantially U-shapedy airtroughs disposed beneath and extending the Cil entire length of the upper run ofthe grate each of which air-troughs communicates with sai'dair-chamber, and a number of rollers mounted on the pins aforesaid between ad-y jacentllinks at intervals transversely of the grate and arranged to run on the upper edges of the sides of the air-troughs aforesaid.

vA chain grate Stoker as claimed in claim 3, in which one of said'steam jets is associated with eachlongitudinal air-conduit, and a plurality of auxiliary jets are provided in said transverse chamber,v one adjacent to the inlet end of each( of thesaid air-troughs. In testimony whereof I aiiiX my signature.

VERNER RUSSELL CHADWICK. 

